Sounding-board bridge for pianos



Feb. 18, 1930. F. MOSER 1,747,729

SOUNDING BOARD BRIDGE FOR PIANOS Filed March 25, 192e 2 sheets-sheet 1 II I I I l 6 M i WMM L A 11 g 12 1 f nnlnlnnnnlnn Qnlnrl/ L 2 11 5 5 i *3fg H97 52 6 7g l 8 /5 9 f Feb. 18, 1930. F. MOSER .1,747,729

SOUNDING BOARD BRIDGE FOR PIANOS Filed March 25, 1926 2 Sheets-Sheet 2Patented Feb. 18, 193() I p UNITED STATES AreNT ori-ICE FELIX MOSER, OFHOLLAND, MICHIGAN SOUNDING-BOARD BREDGE FOR EPIANOS Application iiledMarch 25, 1926. Serial No. 97,284.

The invention relates to improvements in grand piano showi the inventionin plan soundingboard bridges and fastening them and the manner otsecuring the stringplate between the soundingboard and the plate. andsoundingboard to the frame of the piano. The. objects of the improvementare, to pro- Figure l is a cross-section on line A-A ot vide bridgeswhich will, first, improve the Figure 9. v 55 quality of tone by theirgreater resistance and In Figures l and 2 the bridge 3 is a strip of byeliminating the short lengths of strings bewood, similar to the kindcommonly used. tween the plate and the old type bridge, The bridge 3 israbbeted 4 to allow the plate 5 second, will simplify constructionresulting to tit into it, and is fastened to the soundingin greaterdependability, third, will reduce board 6 in the usual way. It is also:fastened 60 cost ot production. to .the plate (5) by screws 8 or bolts9. The The invention consists of the matters herein st rlng l0,stretched over the bridge 3 to the described and pointed out in claims.hitchpin ll, imparts its vibrations through The so-called dead ends ofthe strings, bethe bridge 3 to the soundingboard 6, the ribs tween thebridge and the hitchpins of the .7 acting as conductors of thesevibrations to G5 plate, anywhere between 2 and 6 inches long all partsof the board. The bridge may be are always a source of mostlyundesirable notched to provide accurate stringlengths overtones. andprojects above the plate for that purpose. This dead end is to bepractically elimi- Accurate stringlength may also be obtained nated byextending` or enlarging the string by crosswires l2, in which case thebridge 79' plate so that it will fully or partly cover the may be levelwith the plate. bridge. Plate and bridge will be rigidly fas- Figures 3and l show a sectional bridge 3, tened to each other. Rigidity being theforeconsisting of blocks ot' wood ot convenient most requirement orp apianobridge to stop and size and shape, beingl placed on the sounding- L5 receive the vibration of the usually high tenboard 6, over the ribs 7,on a line where the sioned strings at proper string lengths. bridgeshould be placed. rlhe sections are The plate thus becomes part of thebridge, fastened to the soundingboard 6 and its ribs 7, furnishing mostof that resistance. and to the plate 5, by means of glue, and

In the accompanying drawing, Figures screws S or bolts 9. T he stringl0, stretched 39 1 3-5-7 represent four similar cross-secover thecrosswire l2 to the hitchpin l1, im- 5' tions, showing lfour types ofbridges, all tour parts its vibrations through the plate 5 and involvingthe saine acoustic principle, the bridge 3, to the soundingboard 6, theribs 7 adaptability of each depending on the conactingas conductors ofthese vibrations to all struction and direction of the grain of theparts of the board. soundingboard or whether the plate be made InFigures 5 and G tlie bridge 3 is a strip of ol metal or wood, or uponhigh or low tension wood, of the usual lengthwise shape. The of thescale. bridge 3 is 'fastened to the soundingboard 6 Figures 2-4--6-8represent cross-sections in theusual way, and to the plate 5, by meansen line l-l of Figures 1 -3-5-7 respecof glue, and screwsSor bolts 9.The string l0, tively, showing the bridges on a line across stretchedover the crosswire l2, to the hitchthe strings.k -pin ll, imparts itsvibrations through the `Figures 1-2-3-4 show the bridge in conplate 5,and the bridge 3, to the soundingjunction with a ribbed soundingboard asit is board 6, the bridge 3 acting as conductor of generally used today.The grain of the these vibrations to all parts of the board insoundingboard runs in the same direction absence of the ribs. Withthebridge. :Figures 5-6-7-8 Show Figures 7 and 8 show a sectional bridge 3,the bridge in conjunction with a soundingconsisting of blocks of wood ofconvenient board that is not ribbed. The grain of the size and shape,being placed on the soundingsoundingboard runs crosswise to the bridge.board 6 at convenient distances from each Figure 9 is a view of thetreble side of a other on a line where the bridge should be, @W

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A strip 13 is glued to the other side of the soundingboard 6, on a linecorresponding to the sectional bridge 3. Strip 13, soundingboard 6,bridge 3, and plate 5, are fastened by means of glue, and screws 8 orbolts 9. The string 10, passing over the crosswire 12, to the hitchpin11, imparts its vibrations through the plate 5, and the bridge 3, to thesoundingboard 6, the strip 13 acting as conductor of vibrations to allparts of the board in absence of the ribs.

ln Figures 9 and 10 the plate (5) is fastened to the frame (14) byscrews (15), which run through the blocking or bushings (16), whichregulate the height of the string plate, and through the soundingboard(6) which is glued on to the frame (14).

At B a section ofthe stringplate and soundingboard is broken away toexpose the frame (14) of the piano on to which is glued the outer rim(18'). Forsimplicity only one string to the unison is shown. The strings(10) run from the tuning pins (17) over the cross vwires or elevations(12) to the hitclipins (11).

A sectional bridge (3) asdescribed in Figures 3 and 4 is shown here. Thevarious sections (3) 'are fastened between the stringplate (5) and thesoundingboard (6) by screws which run into the ribs (7).

The main functions of a soundingboarc bridge are: to stop the vibrationsof the strings at the proper stringlength and to convey these vibrationsto the soundingboard, where they are amplified. Y

Rigidity or resistance, being the first requirement of a bridge, isacquired by rigidly fastening the bridge between the plate and thesoundingboard. Either of the bridges or a combination of them lcan beused in either upright or grand pianos, the plate being made of metal orWood or whether the soundingboard be ribbed or not.

This specification applies to treble or bass bridges both.

These bridges relieve the immense strain on the soundingboard and itsribs caused by the downward pressure of the strings on the old typebridges. Thus the sound- -ingboard is able to vibrate more freely andnaturally. The crowning of the soundingboard which is undesirablebecomes unnecessary with these new bridges.

)Vhile wood is preferred for this bridge, the use of metal may beresorted to with advantages, mainly in cost of productionnamely, thebridge may be cast onto the plate, either sectionally or in full lengthand fastened to the soundingboard as explained.

I claim:

1.v In a stringed musical instrument, the combination of a stringplatewith a soundcrosswires for the purpose of terminating the active or livepart of the strings and is glued to a soundingboard; extending saidstringplate into the rabbet of the bridge and fastening said stringplateto the bridge by screws or bolts.

2. In a stringed musical instrument, the combination of a ribbedsoundingboard, a stringplate and a sectional bridge, thesections of thebridge `being placed over each rib of the soundingboard respectively,the stringplate having notches, crosswires or elevations for the purposeof terminating the active or live part of the strings and is extendedover said sections of the bridge, acoustically and mechanically forminga part of said bridge, the soundingboard, stringplate and the sectionalbridge being fastened together by screws or bolts piercing the differentsections of the bridge and the ribs of the soundingboard.

3. In a stringed musical instrument, the combination of a bridge whichis 'fastened to a soundingboard, and a stringplate having notches,crosswires or elevations for the purpose of terminating the active orlive part of the strings, said stringplate being eX- tended and fastenedover the bridge, acoustically and mechanically forming a part of saidbridge.

4. In a stringed musical instrument, the combination of an unribbedsoundingboard having a strip glued across the grain on its reverse sideon a line with the bridge, a stringplate having notches, crosswires orelevations for the purpose of terminating the active or live part of thestrings, and a sectional bridge, the respective sections being placed atconvenient distance from each other between the stringplate and the'1`05soundingboard, said strip and stringplate acoustically and mechanicallyforming a part of said sectional bridge, being fastened together byscrews o r bolts piercing the different sections 'of the bridge and thesoundingboard.

5. In a stringed musical instrument, the combination of a soundingboard,a stringplate and a sectional bridge, the respective sections ofwliichare located on the under` side of said stringplate at convenientdistance from each other and are substantially of the same material thestringplate is made of; said stringplate having Vnotches crosswires orelevations on its upper side for the purpose yof terminating the active'or live part of thev strings, acoustically and mechanically forming apart of said sectional bridge, and is secured to the soundingboard byscrews or bolts, Which pierce the sections of the bridge. y

Y FELIX MOSER.

ingboard bridge, which is rabbeted to fit the corresponding edge of saidstringplate,

i notched on the opposite edge 0r havingV

